Ion beam processing systems for ion implantation of wafers are known. The prior art is familiar for example with systems that scan ion beams across target objects so as to selectively dope the target surface. U.S. Pat. No. 5,028,795, entitled xe2x80x9cIon Implantation Apparatusxe2x80x9d describes one such system, and is hereby incorporated by reference. In the ""795 patent, two multi-pole electrostatic deflectors are used to scan the beam in two dimensions across the target surface.
The prior art is also familiar with magnetically-controlled ion beam scanning systems. U.S. Pat. No. 4,922,106, entitled xe2x80x9cIon Beam Scanning Method and Apparatus,xe2x80x9d describes one such system, and is also incorporated by reference. In the ""106 patent, a magnetic deflector with two truncated sector-shaped poles is used to control the ion beam so as to maintain a parallel beam path and a scan direction.
The prior art is further aware of systems which mechanically scan the target object in one direction, and which electrostatically or magnetically scan the beam in the other direction. In combination, therefore, such systems provide a raster scan that fully covers the target object surface. U.S. Pat. No. 4,726,689, entitled xe2x80x9cLinear Gas Bearing with Integral Vacuum Seal for use in Serial Process Ion Beam Implantation Apparatus,xe2x80x9d describes one related system, and is likewise incorporated by reference. In the ""689 patent, linear gas bearings are used to provide both linear axial motion and a high differential pressure link between ambient pressure and the internal chamber vacuum.
Wafers are typically provided to ion processing systems in a FOUP (front opening unified pod), known in the art. FOUPs are heavily standardized; and so systems must accommodate interfacing to FOUPs. Certain systems process wafers at upwards of 240 wafers/hour; and so the mechanical interface and robotics between the system and the FOUPs are very important.
One problem is that FOUPs are also standardized at a certain height off of the floor. Ion implantation systems, on the other hand, are relatively high, with the scanning beam approximately five feet off of the floor. Thus, a long travel distance exists between the FOUPs and the ion scanning system, resulting in a travel time that conflicts with throughput goals between the FOUPs, the load lock mechanisms, and the ion scanning system.
One object of the invention is to provide a compact load lock system that increases the timing throughput between FOUPs and the ion scanning system. Other objects will be apparent in the description which follows.
In one aspect, a method is provided for processing one or more wafers from a FOUP to an ion processing chamber. A group of wafers is moved from the FOUP by a first end effector and loaded into a load lock by raising the first end effector and by lowering a first load lock door of the load lock at a first atmosphere opened position. The first load lock is then sealed to its sealed position by raising the first load lock door. The load lock is then evacuated; and a second load lock door of the load lock is raised to a vacuum opened position. Finally, a 3-axis robot moves one of the wafers from the load lock to the ion processing chamber.
In another aspect, the group of wafers has one to twenty five wafers.
In still another aspect, the FOUP is selected from one of several (typically four) FOUPs.
In yet another aspect, the step of moving one of the group of wafers to the ion processing chamber includes utilizing a wafer alignment robot.
In still another aspect, the step of loading the group of wafers into a load lock includes selecting and loading into one of a plurality of load locks.
In one aspect, wafers are processed sequentially from the load lock to the ion processing chamber; and then the load lock is sealed so that processed wafers are moved back to an appropriate FOUP.
In another aspect, the method includes the step of lowering the second load lock door to its sealed position by lowering the second load lock door.
In one aspect, the method includes the steps of reloading the wafer from the chamber to the load lock, sealing the load lock by lowering the second load lock door, repressurizing the load lock, lowering the first load lock door, removing the group of wafers from the load lock and transporting the group to the FOUP.
In yet another aspect, a system is provided for coupling wafers within FOUPs to an ion processing chamber. The system includes one or more FOUPs adjacent a robot track section. A vacuum robot section with one or more load locks is also adjacent the robot track section. Each of the load locks has a lower load lock door and an upper load lock door. The lower load lock door is movable between an atmosphere opened position and a sealed position. The upper load lock door is movable between a vacuum opened position and a sealed position. The track section has an ATM robot for moving one or more wafers from one of the FOUPs to a load lock through the lower load lock door in its atmosphere opened position. The system also includes a ion beam processing chamber; and the vacuum robot section has one or more 3-axis robots to move one wafer from a load lock through the upper load lock door in its vacuum opened position to the ion beam processing chamber.